大家来找茬图片对比问题 容错算法怎么写才合适?

#include <windows.h>
#include <math.h>
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR LpcmdLine,int nCmdShow){
    static TCHAR szAppName[]=TEXT("Painter");
    static TCHAR szClassName[]=TEXT("PainterClass");
    HWND hwnd;
    MSG msg;
    WNDCLASS wndclass;
    wndclass.style=CS_HREDRAW | CS_VREDRAW;//风格
    wndclass.lpfnWndProc=WndProc;//*重要*long point to function 指向函数的的长指针 基于该窗口类创建的窗口所使用的窗口函数的入口地址
    wndclass.cbClsExtra=0;//预留额外空间
    wndclass.cbWndExtra=0;//预留额外空间
    wndclass.hInstance=hInstance;//所在程序的实例句柄
    wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);//图标
    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);//图标
    wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);//背景色
    wndclass.lpszMenuName=NULL;//指定窗口类的菜单
    wndclass.lpszClassName=szClassName;//窗口类类名
    if (!RegisterClass(&wndclass))//注册窗口类 需要一个指向windclass的指针
    {
        MessageBox(NULL,TEXT("This program requires Windows NT!"),szAppName,MB_ICONERROR);
        return 0;
    }
    hwnd=CreateWindow(szClassName,//窗口类名称
        TEXT("Painter"),//窗口标题
        WS_OVERLAPPEDWINDOW,//窗口显示风格
        CW_USEDEFAULT,//初始x方向位置
        CW_USEDEFAULT,//初始y方向位置
        CW_USEDEFAULT,//初始x方向大小
        CW_USEDEFAULT,//初始y方向大小
        NULL,//父窗口句柄
        NULL,//菜单句柄
        hInstance,//程序实例句柄
        NULL);//创建参数 可以访问以后想要引用的程序中的数据
    nCmdShow=SW_SHOWMAXIMIZED;
    ShowWindow(hwnd,nCmdShow);
    UpdateWindow(hwnd);
    while (GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return (int)msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    static int cxClient,cyClient,cxBitmap,cyBitmap;
    static HINSTANCE hInstance;
    static BITMAP bmp;
    static HANDLE h;//bmp图片句柄
    static HDC hdc,hdcMemImag;//hdcMemImag是与窗口DC兼容的DC
   

   

     h=LoadImage(NULL,L"C:\\3333.bmp",IMAGE_BITMAP,0,0,LR_LOADFROMFILE);
     GetObject(h,sizeof(BITMAP),&bmp);//得到图片的宽,高等信息,储存在bmp对象*/
   

    switch(message)
    {
    case WM_CREATE:
        COLORREF colleft,colright;//colleft 左边图片的像素点  colright 右边图片的像素点
        int leftR,rightR,leftG,rightG,leftB,rightB,absR,absG,absB;
        hdc=GetDC(hwnd);//得到窗口的DC(hWnd是窗口句柄)
        hdcMemImag=CreateCompatibleDC(hdc);//得到与窗口DC兼容的DC
        SelectObject(hdcMemImag,h);//把得到的DC与图片句柄关联起来
        for (int y=192;y<=639;y++) //坐标是之前已经找好的
        {   

            for (int x=8;x<=505;x++)
            {
                colleft=GetPixel(hdcMemImag,x,y);//获得左边图片的像素点
                colright=GetPixel(hdcMemImag,x+508,y);//获得右边图片的像素点
               

                leftR=GetRValue(colleft);
                leftG=GetGValue(colleft);
                leftB=GetBValue(colleft);
                rightR=GetRValue(colright);
                rightG=GetGValue(colright);
                rightB=GetBValue(colright);
                absR=leftR-rightR;
                absG=leftG-rightG;
                absB=leftB-rightB;
                if (sqrt((DOUBLE)(absR*absR+absG*absG+absB*absB))>45)
                {
                    SetPixel(hdcMemImag,x+508,y,RGB(0,255,0));
                }
            }
        }
        ReleaseDC(hwnd,hdc);//释放GetDC得到的DC
        break;
    case WM_SIZE:
        InvalidateRect(hwnd,NULL,TRUE);
        break;
    case WM_PAINT:

        hdc=GetDC(hwnd);//得到窗口的DC(hWnd是窗口句柄)
        BitBlt(hdc,0,0,bmp.bmWidth,bmp.bmHeight,hdcMemImag,0,0,SRCCOPY);//把图片画在窗体上
        ReleaseDC(hwnd,hdc);

        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    }
    return DefWindowProc(hwnd,message,wParam,lParam);
}